From Energy Efficiency to Carbon Neutrality: A Global Bibliometric Review of Energy Conservation and Emission Reduction in Building Stock

Abstract

As a major contributor to global energy consumption and carbon emissions, the building sector plays a pivotal role in achieving carbon peaking and neutrality targets. This study systematically reviews the evolution of research on building stock energy conservation and emission reduction (BSECER) from 1992 to 2025, which is based on a comprehensive bibliometric analysis of 2643 publications. The analysis highlights the research contributions of countries, institutions, and scholars in the BSECER field, reveals patterns in collaborative networks, and identifies the development and shifting focus of research topics over time. The findings indicate that current BSECER research centers around four main areas: behavioral efficiency optimization, full life cycle carbon management, urban system transformation, and the integration of intelligent technologies, which collectively form a multiscale emission reduction framework from individual behavior to large-scale systems. Building on these insights, this study outlines five key future research directions: advancing comprehensive carbon neutrality technologies, accelerating the engineering application of intelligent technologies, developing innovative multi-scenario policy simulation tools, overcoming integration challenges in renewable energy systems, and establishing an interdisciplinary platform that links health, behavior, and energy conservation.

1. Introduction

1.1. Background

In the face of escalating global climate challenges and environmental degradation, the urgency to decarbonize key economic sectors has reached a critical juncture. The building sector, which accounts for nearly 40% of global energy consumption and carbon dioxide (CO₂) emissions [1], stands at the forefront of sustainable development efforts [2]. This sector’s energy and material intensity—spanning construction, operation, renovation, and demolition—renders it central to national and international climate action strategies.

China presents a particularly compelling case. With projections indicating that China’s total in-use building stock will exceed 75 billion square meters by 2050 [3], the embodied and operational emissions tied to this massive infrastructure footprint require ongoing and intensified mitigation efforts. Cement and steel, the two dominant construction materials in China, are expected to constitute up to 97% of CO₂ emission reductions by 2060 [4], signaling the disproportionate impact of material-related decisions within the building stock. This phenomenon is not unique to China. Similar trends are observed globally: in Switzerland, building stock accounts for 24% of total carbon emissions and 44% of final energy consumption [5]; in the European Union (EU), building stock is responsible for 40% of energy use and 36% of greenhouse gas (GHG) emissions [6]; and the existing buildings in the United States also consume over 40% of the total primary energy [7].

Rapid urbanization in emerging economies further compounds the urgency. Cross-national comparative studies show that, by 2050, China’s existing building energy consumption is projected to be 15 times higher than in 1970, whereas India and Brazil are expected to experience 12-fold and 11-fold increases, respectively [8]. Conversely, developed economies such as those in the EU and North America have slowed this growth through regulatory interventions and energy efficiency improvements [9,10]. This stark divergence in energy trajectories underscores the critical need for research that not only assesses building stock emissions at scale but also formulates regionally adaptive strategies. Specifically, there is a pressing need for scientific frameworks that integrate spatial, temporal, and sectoral dynamics to inform targeted building stock energy conservation and emission reduction (BSECER) pathways.

1.2. Literature Review

The growing interest in building stock energy efficiency and decarbonization has yielded a broad body of research addressing technical, methodological, and policy-oriented dimensions [11,12]. Retrofitting and upgrading existing buildings is widely acknowledged as one of the most cost-effective strategies for reducing emissions [13]. Policy experiments in the EU have further demonstrated that comprehensive renovation initiatives can catalyze significant energy savings and climate benefits [14].

Despite these advances, existing literature exhibits several critical gaps. First, many studies focus on isolated case applications or single-building analyses, lacking a systemic approach to evaluating emissions across large-scale building stock. While inventory modeling has improved the accuracy of energy demand projections and emissions assessments [15], few studies critically interrogate the assumptions behind these models, especially in rapidly urbanizing economies like China. For example, the transposition of European building energy models to the Chinese context often overlooks differences in urban form, construction typologies, regulatory regimes, and socioeconomic development levels [16].

Second, the methodological evolution—from top-down energy accounting [17] to hybrid and bottom-up models [18]—has increased precision but has not sufficiently addressed uncertainty or data scarcity in developing regions. A comparative analysis of these approaches for measuring building floor space illustrates this trade-off: top-down methods provide broad system-level coverage but often lack the accuracy needed for granular policy design. In contrast, bottom-up models offer detailed insights but are heavily constrained by data availability and consistency. The accurate and comprehensive collection of building floorspace data, as well as the development of a global building stock database, remains an unresolved challenge that significantly hampers robust cross-regional analyses [19]. Moreover, although studies on specialized building types, such as heritage buildings [20], have introduced nuanced, context-sensitive solutions, these remain fragmented and often lack integration into broader policy and planning frameworks.

Third, prior studies often treat technical, policy, and governance issues in isolation. Though some reviews have examined energy efficiency policies or individual technologies [21,22,23,24], few have systematically integrated these streams to capture the dynamic interplay between technological evolution, research focus, and policy-making over time. Additionally, while there is increasing awareness of the need for coordinated, systems-level strategies—linking urban planning, building codes, and climate action frameworks [25,26]—most existing work remains descriptive or normative, lacking robust empirical analysis.

In summary, while the BSECER literature has expanded significantly, it remains fragmented and uneven. There is no comprehensive, critically grounded framework that traces the evolution of research themes, identifies persistent knowledge gaps, and reveals how academic inquiry has interacted with global policy priorities over time. This review addresses these gaps by conducting a large-scale bibliometric and thematic synthesis of 2643 publications from 1992 to 2025. It offers a multi-dimensional understanding of BSECER’s development, aiming to inform more coherent, context-sensitive strategies for the decarbonization of global building stock.

1.3. Objectives and Novelty

By mapping the evolution of research themes, collaborative networks, and policy–technology synergies, this study aims to bridge critical gaps in understanding how building stock decarbonization can contribute to carbon peaking and neutrality targets. This review addresses three pivotal questions:

• Research landscape: What are the temporal and spatial patterns of BSECER research? Which countries, institutions, and journals dominate knowledge production, and how do interdisciplinary collaborations shape the field?
• Evolutionary trends: How have research foci shifted across key stages—from operational energy efficiency to life cycle carbon management and system integration? What emerging technologies are driving the latest paradigm shifts?
• Policy-research nexus: How do policy interventions and academic research dynamically interact to accelerate building stock decarbonization? What are the regional disparities in policy responsiveness and implementation?

The key contribution and novelty of this review lies in offering the first large-scale bibliometric and qualitative synthesis of global BSECER research. Unlike prior reviews that focused narrowly on technology, retrofitting, or policy design, this study integrates technical, institutional, and policy dimensions across three decades of research. It reveals a significant paradigm shift in the field—from a traditional focus on “energy efficiency” to a more strategic, integrated vision of “carbon neutrality”, rooted in life cycle thinking and systems coordination.

Importantly, this review also identifies and analyzes the feedback loops between scientific innovation and regulatory development, offering new insights into how academic discourse and policy agendas co-evolve. By mapping these dynamics, the study bridges a theoretical gap in understanding the reciprocal influence between research and governance in the context of building stock decarbonization. These findings provide not only an intellectual foundation for future research but also strategic guidance for policymakers seeking to align science, technology, and policy for a low-carbon built environment.

2. Data and Methodology

To effectively map the landscape and emerging hotspots of BSECER research, this study followed established bibliometric methodologies for data collection and preliminary analysis. The Web of Science (WOS) Core Collection was selected as the primary database and included four indices: the Science Citation Index Expanded (SCI-EXPANDED), Social Sciences Citation Index (SSCI), Arts & Humanities Citation Index (A&HCI), and Emerging Sources Citation Index (ESCI). Given the generally greater academic rigor and depth of peer-reviewed journal articles, this study limited the search to research articles, review articles, and early access publications [27]. This study used a series of concepts or topics related to building stock, energy consumption, and carbon emissions as search terms, and the wildcard “AND” was added to ensure search inclusiveness.

The search terms covered a range of concepts related to building stock, energy consumption, and carbon emissions. Logical operators such as “AND” were used to ensure inclusivity in the search results. The search was conducted on March 21, 2025, yielding 3182 articles. After the dataset was refined via the “Refine results” tool in WOS (Figure 1), 2643 relevant articles were retained for analysis. For bibliometric analysis and visualization, this study employed tools such as Cite Space v6.2. R6, Gephi 0.1, and VOS viewer 1.6.11.

3. Scientometric Features of the Literature

3.1. Quantity Analysis of Published Articles

Our findings (Figure 2) show that research on BSECER has evolved in distinct phases. The earliest literature dates back to 1992, followed by a long period of limited activity. An increase occurred in 2005, likely in response to the entry into force of the Kyoto Protocol, which imposed binding emission reduction targets on signatory countries, catalyzing research into energy efficiency in the building sector [28]. This was further amplified by preparations for the IPCC Fourth Assessment Report and the IEA’s evaluation of building energy efficiency policies [29].

Between 2005 and 2019, the global research output on BSECER steadily increased. The COVID-19 pandemic in late 2019 marked a turning point, introducing both challenges and new research directions. A surge in publications between 2020 and 2021 reflects scholarly interest in adapting building energy use strategies in response to shifts in occupancy patterns, ventilation needs, and indoor environmental quality.

Notably, China’s sharp increase in publication volume after 2021 coincided with the announcement of its “dual-carbon” goals—to peak carbon emissions before 2030 and achieve carbon neutrality by 2060. As the building sector accounts for approximately 40% of China’s total emissions, its decarbonization has become a strategic research priority.

3.2. Country/Region Collaboration Network Analysis

Global research on BSECER has a three-tier citation structure (Figure 3). China leads with 17,116 citations (31.2% of the global total), driven by both a high number of publications (601 articles) and improved research quality. The United States (10,785 citations) and the United Kingdom (9003 citations) followed, together accounting for 67.3% of global citations and forming a “golden triangle” of knowledge influence.

The secondary hubs include European countries such as Germany (2634), the Netherlands (3306), and Italy (3748). Notably, citation performance varies widely: for example, Russia has contributed uniquely valuable insights into building energy efficiency in extreme climates [30], whereas Thailand and Israel have achieved high-impact outputs by focusing on niche technologies such as passive cooling in humid climates [31]. A regional analysis reveals three major cooperation clusters: the East Asian technology circle (China, Japan, South Korea), the European policy circle (Germany, the Netherlands, Switzerland), and the North American evaluation circle (U.S., Canada).

Collaboration strategies vary by country and fall into four types (refer to

Table 1. The cooperation strategies of different countries.

Cooperation Type	Representing Countries	Cooperative Features	Typical Manifestation
Global hub	China, the U.S.	Wide and balanced global cooperation	China establishes cooperation with 50 countries
Regional dominant	Germany, Australia	Localized cooperation and selective international links	Cooperation between Germany and Europe accounts for 63% of Germany’s total cooperation
Professional focus	Switzerland, Denmark	High intensity and precise cooperation	Switzerland cited 34.7 (top 5 globally)
Emerging development	Saudi Arabia, Malaysia	Rapidly expanding collaborative network	Saudi Arabia’s international cooperation volume increases by 28% annually

): global hubs (China, U.S.), regional leaders (Germany, Australia), niche experts (Switzerland, Denmark), and emerging contributors (Saudi Arabia, Malaysia). Internationally coauthored papers average 34.6 citations, 62% higher than domestic collaborations. The Switzerland–Germany collaboration stands out, with a normalized citation score of 2.31.

3.3. Institution Collaboration Network Analysis

The data from publishing institutions reveal that a multi-centered and hierarchical international cooperation network has taken shape in the field of BSECER (see Figure 4). Chinese research institutions occupy the core position in this network, with the Chinese Academy of Sciences (total connection strength: 46) and Tsinghua University (cooperation strength: 34) forming China’s dual hubs, leading basic research and applied innovation, respectively. Notably, the cooperation strength between the Chinese Academy of Sciences and its affiliated university (University of Chinese Academy of Sciences) has reached 17, far exceeding the international average, reflecting the large-scale collaborative model characteristic of Chinese science. Moreover, Chongqing University has emerged as a unique international bridge, with cooperation strength reaching 6, with both the University of Reading (UK) and Lawrence Berkeley National Laboratory (U.S.) surpassing even the strength of collaboration between the Chinese Academy of Sciences and Berkeley (4). This suggests that certain Chinese universities have developed international cooperation channels parallel to traditional central research institutions.

The network analysis of publishing institutions identified three distinct cooperation clusters: (1) the China–Europe Technology Alliance (e.g., Chongqing University–Leuven University, intensity 6; ETH Zurich–Politecnico di Milano, intensity 4), which focuses on innovation in building energy-saving technologies; (2) the North American Standard R&D Network (e.g., Lawrence Berkeley National Laboratory–University of Colorado, intensity 2), which focuses on evaluation system development; (3) the Asian Policy Research Circle (e.g., Hong Kong Polytechnic–National University of Singapore, intensity 1), which emphasizes regional adaptation strategies. This spatial distribution aligns closely with technology–policy–geography coupling theory, which posits that technology-leading institutions tend to cluster spontaneously, whereas policy-driven collaboration is typically regionally organized.

A time series analysis based on average publication years (2017–2023) indicates that the research peak for traditional European and American institutions (e.g., Oxford University and UC Berkeley) was concentrated between 2017 and 2019, with average citation counts ranging from 76 to 120. In contrast, Chinese institutions (e.g., the China Academy of Building Research and Hunan University) have shown increased activity from 2021 to 2023. Notably, Hong Kong Polytechnic University (average publication year: 2021) maintains high-intensity collaboration with MIT (intensity 2) and Tsinghua University (intensity 1), suggesting the emergence of a new east–west knowledge flow pathway. Citation analysis reveals that while American institutions such as the University of Colorado produce fewer papers (total intensity: 7), their average citation count is high (120), aligning with the elite innovation diffusion model. Conversely, the broader collaboration network and greater output of Chinese institutions (e.g., 59 publications from the Chinese Academy of Sciences) exemplify a scale–network synergy effect.

3.4. Top-Tier Journals

The research on BSECER exhibits a clear trend of journal centralization, as shown in Figure 5. Energy and Buildings holds an overwhelmingly dominant position, publishing 265 articles (9.996%), far surpassing other journals and highlighting its authoritative status in building energy research. This journal has long focused on building energy simulation, energy-saving technologies, and policy evaluation, becoming the preferred publication platform in the field. Sustainability (202 articles) and the Journal of Cleaner Production (175 articles) emphasize sustainable development and life cycle analysis, together forming a tripartite framework of technology, environment, and policy. Journals such as Applied Energy (112 articles) and Building and Environment (93 articles) also show strong performance in specialized areas such as energy system optimization and the physical environment of buildings, collectively shaping the core knowledge dissemination system.

Our analysis reveals strong interdisciplinary characteristics in BSECER research. Traditional energy journals such as Energy and Renewable Energy remain influential. Simultaneously, journals in environmental science (Science of the Total Environment), policy research (Energy Policy), and urban sustainability (Sustainable Cities and Society) are becoming key platforms, reflecting a shift from a technology-focused to a multidimensional research framework that includes policy and societal aspects.

Moreover, emerging open-access journals, Buildings (86 articles) and the Journal of Building Engineering (65 articles), have shown rapid growth, with publication volumes increasing by 473% and 200%, respectively, in the past five years. This reflects how shifts in publishing models are reshaping the academic dissemination landscape.

From a geographical perspective, European publishers such as Elsevier and Springer remain dominant, with their journals accounting for 7 of the top 10. Dutch journals such as Energy and Buildings and Applied Energy are notable for combining high output with high impact (Cite score > 7.9). In contrast, North American journals such as Environmental Science & Technology have fewer publications (21 articles) but demonstrate greater per-paper influence (Cite score: 11.4), reflecting a scholarly tradition of quality over quantity.

Asian journals are also gaining prominence. For example, Sustainable Cities and Society (Singapore) has published 75 articles, becoming a key outlet for regional policy studies. Although Building Simulation (China) is not yet in the top 30, it has shown consistent annual growth of 25%, indicating a rising academic voice in Asia. Overall, while technological research continues to dominate (73% of publications), research focused on policy and societal dimensions (9%) shows strong potential, especially in urban sustainability.

3.5. Author Collaboration Network Analysis

This study employs social network analysis to examine the structure and evolution of author collaboration in the BSECER field (Figure 6). The collaboration network demonstrates multicentered clustering. Chinese scholar Cai Weiguang (total connection strength: 38; 18 publications) and European scholar Hertwich Edgar G. (international cooperation strength: 13) anchor the field’s two major nodes in East China and West China, forming a bipolar leadership pattern. Chinese scholars are further subdivided into three regional clusters: Beijing, South China, and emerging young scholars. In contrast, European scholars exhibit a greater tendency for cross-border collaboration, such as between Norwegian and Swiss researchers. This reflects the regionally differentiated development of building energy efficiency research.

There is a strong positive correlation between cooperation intensity and academic influence. Authors with high collaboration intensity (>5) publish an average of 8.2 articles, compared with 4.3 for those with lower intensity. Moreover, their papers receive 427 average citations, which is 4.3 times greater than those of their lower-intensity counterparts. International co-authored papers are particularly impactful, averaging 427 citations, compared with 215 citations for domestic collaborations, highlighting the value of cross-border knowledge exchange.

From a temporal perspective, author networks reveal clear intergenerational evolution. Between 2015 and 2019, research was primarily theoretical and led by scholars such as Sandberg. Between 2020 and 2022, mid-career scholars such as Cai drove methodological innovation. After 2023, younger researchers such as Ma Minda began focusing on technological applications (average publication year: 2023.2). This evolution reflects the broader transition in BSECER research—from theoretical frameworks to practical solutions.

4. Holistic Insight into the Evolution of Building Stock Research

4.1. Topic Distribution and Evolutionary Trends

From the time zone chart of keywords (see Figure 7), the core direction of research on BSECER centers on energy efficiency improvement and carbon emission control. High-frequency keywords such as “performance” (377 times), “CO₂ emissions” (335 times), and “energy consumption” (293 times) clearly reflect this focus. Moreover, “lifecycle assessment” (232 times) and “energy efficiency” (211 times) indicate that life cycle thinking and optimization remain the primary research methods. At the technical level, studies predominantly focus on energy management (255 times for “energy” and 107 for “renewable energy”), emission control (160 for “carbon emissions” and 149 for “climate change”), and optimization strategies (162 for “optimization” and 125 for “simulation”).

With respect to research objects, residential buildings (185 times) and public buildings (38 times) emerge as the primary carriers of study, whereas research at the urban scale (46 mentions of “urban” and 134 of “city”) is gaining increasing attention. In terms of policy support, keywords such as “policy” (69 times) and “management” (49 times) highlight the importance of institutional frameworks. Notably, the application of emerging technologies, such as “machine learning” (first appearing in 2018) and “digital twins” (2024), along with the rise of sustainable design concepts such as “green buildings” (2018), is pushing the field toward intelligent, digital, and sustainable transformation.

From a temporal perspective, the staged emergence of keywords is consistent with the features of the time zone map. The evolution of research hotspots in energy conservation and emission reduction for building stock reveals three distinct development stages, identifiable through keyword burst intensity analysis (see Figure 8).

• Early Basic Exploration (2005–2010). During this period, scholars began to systematically investigate the role of the building sector in global energy consumption and carbon emissions. Keywords such as “energy efficiency” (intensity: 4.4, 2005–2013) and “global warming” (intensity: 4.03, 2007–2010) were frequently cited, especially in the environmental science literature. The exceptionally high burst of the keyword “building stock” (intensity: 11.99) suggests major progress in constructing building stock data systems, aligning closely with the implementation of the EU Energy Performance of Buildings Directive (EPBD 2002/91/EC), highlighting the direct influence of regulatory frameworks on foundational data development.
• Mid-term technological deepening stage (2010–2021). As emission reduction policies became more stringent, research shifted toward specific technologies and management strategies. There was a noticeable rise in citations related to policy concepts (e.g., “carbon neutrality”) and technical applications (e.g., “dynamic simulation”). Keywords such as “dynamic simulation” (intensity: 3.84, 2016–2020) and “retrofit” (intensity: 3.88, 2018–2021) reflect the growing academic efforts to quantify operational-phase carbon emissions and develop refined energy management tools. During this stage, the focus expanded to practical domains, including energy-saving retrofits and dynamic simulation modeling. The research outcomes informed the development of green building standards, such as LEED and the Building Research Establishment Environmental Assessment Method (BREEAM), and laid the foundation for a new paradigm of technology and policy synergy.
• System integration stage (2021 present). This current phase is characterized by technological convergence and a focus on multi-objective collaboration and interdisciplinary integration. The keyword “scenario analysis” reached a record burst intensity that was 26% higher than that of “climate change”, highlighting its growing significance in achieving carbon neutrality targets. Concurrently, the emergence of terms such as “artificial intelligence” (intensity: 3.61) and “circular economy” (intensity: 4.66) points to a multidisciplinary shift, indicating a closer integration between energy efficiency research, carbon neutrality pathways, circular economic models, and intelligent technologies.

Although the keyword “carbon neutrality” (intensity: 4.86) has only appeared in recent years (2022–2023), its burst strength shows an annual growth rate of 142%, closely mirroring the global carbon neutrality pledges of more than 130 countries and highlighting the urgency of policy-driven research responses.

Furthermore, this study employed tools such as Cite Space v6.2. R6, Gephi 0.1, and VOS viewer 1.6.11. These tools helped us to observe a 3–5-year lag between major policy milestones, such as the Paris Agreement, and the emergence of corresponding research hotspots, suggesting that academic output typically requires a gestation period to align with policy directions. Interestingly, the average duration of policy-related keywords is 3.8 years, which is significantly shorter than that of technology-related keywords (6.3 years), revealing a structural difference: policy themes often evolve quickly in response to shifting international agreements or national strategies, whereas technology-related terms sustain influence over longer periods owing to the lengthier research and development cycles and consistent application contexts.

4.2. Coupling Analysis of Technology Pathways and Policy Objectives

Academic research and policy formulation in the field of building stock exhibit significant collaborative evolution characteristics. Through the temporal analysis of the emergence of research hotspots and policy implementation from 2005 to 2025 (see

Table 2. Timetable for the coupling of academic research and policy.

Time Period	Academic Research Explosion Field (Burst Keywords/Intensity *)	Key Policy/Regulatory Milestones
2005–2013	energy efficiency, 4.4	EU: Energy Performance of Buildings Directive (2002/2010 revised) U.S.: The Energy Policy Act of 2005 (2005) China: Regulations on Energy Efficiency of Civil Buildings (2008)
2006–2015	climate change, 9.18	Kyoto Protocol (2005) England: Climate Change Act 2008 (2008) U.S.: California Global Warming Solutions Act of 2006 (2006)
2010–2017	CO2 emissions, 7.19	EU Emissions Trading System Phase II (2008–2012) China’s Pilot Emissions Trading Schemes in Seven Provinces and Cities (2013) Korea Emissions Trading Scheme Launch (2015)
2016–2020	urban, 4.51	Paris Agreement (2015/2016) China: Urban Climate Change Adaptation Action Plan (2016) C40 Cities Climate Leadership Group Expansion (2016)
2018–2021	retrofit, 3.88	EU: Renovation Wave Strategy (COM/2020/662 final) U.S.: Infrastructure Investment and Jobs Act (Public Law 117-58) Japan: Act on Improvement of Energy Consumption Performance of Buildings (Revised 2019)
2020–2023	scenario analysis, 5.79	China: Dual Carbon Goals: Carbon Peak by 2030 & Carbon Neutrality 2060 (Proposed in 2020) EU: Fit for 55 Package (2021) India: National Hydrogen Mission (Approved 2021)
2021–2025	circular economy, 4.66	EU: Circular Economy Action Plan (COM/2020/98 final) China: 14th Five-Year Plan for Circular Economy Development (NDRC 2021) U.S.: California Plastic Pollution Prevention and Packaging Producer Responsibility Act (SB 54)
2022–2025	carbon neutrality, 4.86	U.S. Inflation Reduction Act of 2022 (Public Law 117–169) Germany: Building Energy Act (2023) ASEAN Strategy for Carbon Neutrality (2022)

Note: * Intensity (also referred to as Strength) represents the burst intensity of a keyword, calculated based on the increase in its frequency over time. It indicates the degree of sudden academic attention the keyword received during its burst period, consistent with the definition of “Strength” provided in Figure 8.

), it can be clearly observed that policy signals have a guiding effect on academic research, as does the feedback mechanism of research results on policy iteration. This two-way interaction represents a unique evolutionary path in different technological fields and with different regional backgrounds.

This study employed tools such as Cite Space v6.2. R6, Gephi 0.1, and VOS viewer 1.6.11. They found that there is significant dynamic coupling between research and policy-making in the field of BSECER. From a temporal perspective, 75% of research surges occur within a 1–2-year window following policy implementation. This is particularly evident in the case of the EU Renovation Wave Strategy, where building renovation research experienced a notable surge. Within 18 months of the policy’s release, the number of related publications increased by 217%, reflecting the strong guiding influence of policy signals on academic output. Differences in response speed are noteworthy: research on carbon pricing policies responds most rapidly (within approximately 8 months), whereas studies related to energy-efficiency-standard policies show a comparatively delayed response (14.5 ± 3.8 months), which is largely dependent on the leverage effect of policy tools and the level of market participation.

Regional comparisons reveal diverse patterns in the interaction between policy and research. The EU has demonstrated a strong model of policy leadership, with a 62% co-occurrence rate between policy and research keywords. This high degree of alignment is attributed to the EU’s “legislation-standards-funding” trinity mechanism. In contrast, China and the United States have adopted a more market-sensitive, tripartite driving model. For example, the Inflation Reduction Act (IRA) in the U.S. triggered a 570% increase in venture capital in the field of building carbon capture technologies and led to a simultaneous surge in patent applications (up 45%) and academic publications by enterprises (up 38%), illustrating the multidirectional empowerment of policies, markets, and research. In China, engineering demonstration projects play a bridging role, as evidenced by the 1:0.7 ratio between the number of academic papers and demonstration projects in research related to photovoltaic (PV) building integration.

The recent innovation trend in policy instruments is particularly noteworthy. Since 2020, incentives for technological innovation have become central to policy design. For example, the United States has introduced a carbon capture tax credit of USD 85 per ton under the IRA, directly facilitating the deployment of 12 new technologies in building applications. The EU has tripled research output related to EPD certification by implementing a mandatory carbon footprint disclosure system. Moreover, China has increased the proportion of research focused on dynamic carbon accounting models from 9% to 34% within two years through a standard-first strategy. This shift signals a broader transition in policy orientation—from basic regulatory constraints to the nurturing of an innovation ecosystem.

The standardization process and research evolution exhibit strong synergy. In particular, the field of building carbon accounting is undergoing a three-stage transition: from foundational methodologies to specialized tools and, finally, to intelligent algorithms, with machine learning applications growing by 62% annually. The current competition between the EU level(s) framework and China’s Building Carbon Emission Reduction Accounting Standards has further accelerated the iterative innovation of research methodologies. The spiral of progression–standard iteration, research breakthrough, and standard upgrade has emerged as a core driving force behind the development of the field.

4.3. Core Discovery of the Building Stock

On the basis of the analysis of keyword clustering and literature data (Figure 9), the following core conclusions can be drawn:

4.3.1. Behavioral and Operational Efficiency

Research shows that the energy-saving transformation of building stock has significant potential in reducing carbon emissions [2,32]. The co-occurrence intensity of high-frequency keywords such as “retrofit” and “residential buildings” is relatively high, and BSECER requires a multidimensional analytical framework [33].

From a behavioral perspective, studies reveal that occupant behavior and its interaction with energy–carbon factors significantly impact household energy use [34,35]. This complexity has been validated across regions: Japanese residential policies are constrained by behavioral heterogeneity [36], residential carbon emissions in the U.S. are influenced by climate and economic factors [37], and household energy demand in China is rapidly increasing [38]. Notably, the effectiveness of technology promotion is often influenced by behavior; for example, the energy savings of smart meters may deviate from theoretical expectations [39], heat pump adoption depends on policy support [40], and low-income household upgrades yield unique marginal benefits for emission reductions [41]. These findings underscore the essential role of behavioral interventions in energy conservation.

Operational emissions account for the majority of a building’s life cycle carbon footprint [42,43], with heating, ventilation, and air conditioning system optimization playing a particularly critical role [44,45]. Technologies such as air heat recovery can greatly reduce energy consumption [46], but accurate environmental assessments require a comprehensive evaluation of both embodied and operational energy [47]. Regional variation is significant [48]: Northwest China has the highest emission reduction efficiency [49], whereas southern China has relatively high energy consumption levels [50,51]. Globally, residential carbon intensity has decreased by 1.2% annually [52], highlighting the need for locally tailored technology applications. Even with advanced technologies [53], deep decarbonization must also involve energy efficiency improvements and behavioral changes [54], leading to a shift in research toward systemic solutions involving electrification [55] and terminal energy optimization [56,57] However, electrification rates do not always contribute positively to the commercial building decarbonization [58]. Scholars have developed numerous methods to evaluate building energy efficiency, with key indicators including energy performance [59,60] and environmental performance [61], and they have also developed various carbon emission prediction models [62,63].

With respect to operational efficiency, the effects of building energy retrofits vary significantly by region [64]. Case studies on school buildings have shown that upgrades such as envelope improvements and lighting systems require climate-specific parameter adjustments [65]. Near-zero energy renovations in Spain’s cold climate zones highlight the importance of climate-adaptive design [66]. In terms of technology selection, UK research confirms the benefits of window replacement and airtightness enhancements [37,67], while China faces the dual challenges of technological transformation and policy alignment [68]. Economic evaluations suggest that progressive retrofit models [69,70], coupled with new decision-making tools [71,72,73], can improve the sustainability of retrofit projects. Currently, intelligent retrofitting is reshaping the path to energy efficiency through methods such as building information management (BIM)-based energy prediction [74], standardized efficiency evaluation [75,76], data quality optimization [77], automation system application [38,78] and full-chain management solutions such as the fuzzy multiple attribute decision-making (FMADM) model [69], and hybrid energy strategies [34].

From a regional comparative perspective, building carbon emission trends vary widely. U.S. commercial building emissions continue to rise [79] while similar buildings in China show a downward trend [41,80], and Spain excels in decarbonization efficiency [81]. Residential energy use presents greater complexity [82,83]. Portuguese studies link inefficiency to energy poverty [84], while studies in Spain and Luxembourg confirm the synergistic effects of building characteristics, energy use patterns, and policy tools [36,85]. The north–south variation in hybrid vehicle energy use in China [86] and London’s energy pattern recognition model [87] both suggest that technical performance is regulated by climate and behavior. Cold-climate studies have confirmed that optimizing envelope structures can significantly improve efficiency [65,88]. Spanish EPC data have established a quantitative link between energy use and climate zones [59], whereas Italian studies have provided a scientific basis for regional air quality policies [89]. Collectively, these findings emphasize that building retrofit strategies must consider regional climate characteristics.

4.3.2. Life Cycle and Embodied Impacts

Traditional research has focused primarily on energy consumption during the operational stage of buildings, whereas the current trend is gradually shifting toward full-life-cycle carbon emission analysis. The high frequency of keywords such as “embodied carbon” and “life cycle assessment (LCA)” indicates that scholars are increasingly emphasizing the carbon footprint associated with building material production, construction, and demolition.

The construction materials used in buildings have significant and growing implications for global material flows and emissions [90]. The embodied carbon emissions of load-bearing structural materials in building stock have a notable impact on urban sustainable development [91]. A Norwegian study using dynamic material flow analysis demonstrated that substantial differences arise when different LCA principles are applied to future emission calculations [92]. The scale of life-cycle-based energy efficiency assessment models spans from newly built single-family houses [71] to neighborhoods [93] and urban scales [94], with some studies even extending to the African context [95]. It is worth noting that renovation can minimize the need to expand building stock, thereby promoting decarbonization in the building sector [96].

Research on the life cycle carbon emissions of building materials shows that improving material efficiency could reduce cumulative global GHG emissions by 2050, with residential buildings and passenger vehicles contributing to reductions of 20–52 gigatons (Gt) CO₂ equivalent and 13–26 Gt CO₂ equivalent, respectively [97]. This potential is further unlocked through waste recycling: case studies in Indonesia show that concrete recycling reduces environmental impacts [98], whereas prefabricated buildings highlight the full-life-cycle advantages of industrialized construction [76]. Steel flow research identifies key areas such as the building sector [99], whereas a Swedish case study underscores that biobased materials must be synergistically integrated with other technologies [100], emphasizing the need for a comprehensive solution.

In terms of quantitative evaluation, the research accuracy has improved significantly. The Geneva case shows that optimizing building structures can reduce GHG emissions per unit area by 14% [91], whereas geographic information system (GIS) models indicate that common renovation measures can lead to up to 31% emission reduction [101]. At the macro level, there are Chinese research projects in which supply chain optimization could reduce embodied carbon by 49% by 2060 [102]. However, policy implementation remains a challenge: voluntary tools have limited effectiveness [103], current strategies fall short of the 1.5 °C target [104], and EU case studies also demonstrate obstacles to full transformation [105]. These findings highlight the urgent need for policy innovations.

Current studies have established a systematic evaluation framework, focusing primarily on three dimensions. First, in the area of LCA, methods based on sustainable development goals [106] and neighborhood-level databases [107] have broadened the scope of analysis. The Iranian [108] and Peruvian [109] cases have confirmed their policy relevance, although data standardization still requires improvement [110]. Second, in terms of tool integration, BIM-based analysis reveals that nonoperational stages account for 30–50% of total emissions [111]. Third, in the domain of dynamic modeling, frameworks such as the carbon budget model [112] and the Type–Cohort–Time model [113] support policy design, whereas the Regional Assessment of Buildings’ Material Intensities (RASMI) method [90] addresses data gaps globally.

Additionally, economic modeling has confirmed the effectiveness of market mechanisms, and predictive frameworks have enhanced the reliability of both carbon emission [114] and energy consumption forecasts [115]. The Norwegian case [54] further reinforces the importance of coordinating technology, behavior, and energy systems, offering both methodological consensus and practical guidance for emission reductions in the building sector.

4.3.3. Urban Systems and Macro Transitions

At the technical level, emission reduction in building stock depends on the large-scale application of renewable energy. Keywords such as “renewable energy,” “solar energy,” and “heat pump” hold prominent positions in cluster analysis, reflecting the popularity of PV power generation, ground source heat pumps [116], and other technologies in building energy-saving transformations. Additionally, the high weights of keywords such as “integration” and “system” indicate that the optimized design of multi-energy complementary systems (e.g., “photovoltaic + energy storage + smart grid”) is a key future research direction. However, balancing technological feasibility with economic viability remains a major challenge in practical implementation.

Currently, global energy conservation and emission reduction efforts exhibit multiscale and multidimensional complexity. From the perspective of emissions trends, although 80% of global residential buildings have reached peak carbon emissions, achieving carbon neutrality requires the building sector to peak entirely and adopt carbon-negative technologies by 2026 [117,118]. Moreover, regional disparities are significant: cooling demand in developing countries is increasing rapidly, whereas heating-related emissions in developed countries are gradually declining [119,120]. In China, provinces such as Beijing and Yunnan have taken the lead in achieving peak construction-related emissions [76], whereas cities such as Chongqing may struggle to meet their targets in time [121,122], illustrating the complex interrelationship between the energy structure and urbanization [123].

In terms of implementation, various innovative tools show great potential. Technologies such as GIS [124], urban form optimization (e.g., compact layout [125,126]), and community energy systems [127,128] provide technical support for low-carbon transitions. These practices underscore the importance of a multilevel governance system, requiring the coordinated integration of national policy guidance, region-specific management, and urban technology innovation [129].

Further analysis reveals that the driving forces behind transformation are multidimensional, involving policy, technology, and socioeconomic factors. At the policy level, tools range from Iran’s subsidy reforms [130] to ASEAN green finance [131] and China-EU policy coordination efforts [132,133,134], illustrating the diversity of strategies. At the technical level, innovations such as urban metabolic models [135] and intelligent management systems [136] are continuously emerging. At the socioeconomic level, structural changes such as industrial relocation [137], urban expansion [138], and the dynamic balance of carbon emissions [139] must be addressed holistically. Additionally, resource recycling [81,140] offers promising breakthroughs for sustainable urban transformation.

In terms of research methodology, recent advances in modeling have significantly improved prediction accuracy [80,140]. A Norwegian case study confirmed the synergistic effects of transformation strategies and renewable energy [141]. Climate change research stresses the need for regionally differentiated responses [142], whereas Greece’s experience highlights the critical role of increasing renewable energy penetration in achieving deep emission reductions [143].

4.3.4. Technology and Infrastructure Systems

Energy conservation and emission reduction in building stock rely not only on technical means but also on policy guidance and user behavior. The strong correlation between the keywords “policy” and “building energy efficiency research” indicates that measures such as carbon taxes, subsidies, and green building standards play crucial roles in driving transformation.

Technological innovation in this field centers on three key directions: renewable energy application, intelligent technology integration, and low-carbon infrastructure development. With respect to renewable energy, rooftop PV systems have demonstrated significant emission reduction potential. For example, Dutch research has shown that PV generation can increase from 3.86 Tera Watt hour (TWh) to 19.52 TWh, covering 43–57% of residential buildings and reducing CO₂ emissions by 11.32 million tons [144]. In China, the theoretical emission reduction from urban PV applications can reach 4 billion tons [145]. The building characteristics directly impact system performance. The Wuhan case shows that spatial layout affects PV output [146], whereas the Bangladesh Airport case confirms the economic and environmental benefits of utilizing idle land for PV installations [147]. Significant breakthroughs have been achieved in hybrid energy systems: the Libyan case recorded an annual emission reduction of 7800 tons of CO₂ [148], and Iran’s solar cogeneration system confirmed the benefits of distributed energy [108]. Research on community energy hubs further highlights the importance of system integration [149]. Additionally, technologies such as green roofs [150], biohydrogen production [151], and the LCA-GIS integration method [152] collectively expand the sustainability potential of building waste management.

The integration of intelligent technologies is reshaping the pathways for energy-saving transformations in buildings. Some scholars have developed bottom-up models for assessing the energy performance of residential stocks, which are effective tools for supporting stakeholder decision-making [153]. By combining real-time data interaction [154] with 3D urban energy simulation, digital twin technology introduces a new paradigm for smart city planning [155]. In energy modeling, data-driven models [120] and classification frameworks [156] significantly improve prediction accuracy, whereas multilayer consumption analysis [94] and morphological parameter models [153] offer insights into the spatial dynamics of energy use. These advancements strongly support practical transformation efforts: Sweden has balanced heritage preservation with efficiency in historic buildings [157], Germany has validated the synergy between deep insulation and heating system upgrades [158], and China has demonstrated success through combined policy incentives and renewable energy adoption [159], together forming a comprehensive technical chain from monitoring to implementation.

As a key enabler of these technologies, low-carbon infrastructure shows strong potential in transportation, logistics, and regional energy systems. In China, cement transport emissions research highlights the need for emission reduction in eastern regions [144], whereas a Spanish case study proves the environmental benefits of sustainable transport integration [160]. For regional energy system optimization, German research emphasizes the balance between heating demand and supply [158], and both China and the U.S. have developed coordinated pathways integrating power generation, decarbonization, and energy efficiency [115].

4.4. Characteristics of Interdisciplinary Integration

An overlay of citing and cited journals map analysis can visually display the interdisciplinary knowledge flow between citing journals and cited journals. On the overlay map of citing and cited journals, the left side displays the set of citing journals, while the right side shows the set of cited journals, providing a macroscopic view of the relationship between the knowledge frontier and the knowledge base. The curves are citation lines used to show the correspondence between citations. In the figure, the longer the horizontal axis of the ellipse, the more papers published in the corresponding journal; the longer the vertical axis of an ellipse, the more authors it represents. The z-score marked on the curve is a standardization of the f-value, which represents the citation frequency.

As shown in Figure 10, the disciplinary distribution of cited journals is mainly concentrated in the fields of veterinary and animal science, while the cited journals exhibit three distinct knowledge domain characteristics: (1) Environmental, Toxicology, and Nutrition; (2) Economics, Economic, and Political; (3) Earth, Geology, and Geophysics. It is worth noting that the distribution curve of the applied disciplines shows a significant convergence trend, indicating that the birth of this emerging discipline essentially integrates the knowledge foundations of the three fields mentioned above, reflecting a typical interdisciplinary development model— that is, promoting the formation of new disciplinary fields through the intersection and fusion of multidisciplinary knowledge.

The intensive citation pathway from the cited journals (Veterinary, Animal, Science) to the citing journals (Environmental, Toxicology, Nutrition) indicates that research on energy conservation and emission reduction in animal husbandry is closely aligned with environmental science. This suggests that the research focus in this field includes GHG emission control in aquaculture (e.g., methane reduction), environmental toxicological risk assessment in waste management, and nutritional strategies for feed optimization. For example, previous studies have quantified the carbon footprint of the entire livestock industry chain via LCA [161] and explored the environmental impacts of different feeding patterns [162].

In addition, the citations of economics and political science journals (Economics, Economic, and Political) by the cited journals reflect the important role of policy tools and economic incentive mechanisms in promoting energy conservation and emission reduction. For example, some scholars have analyzed the impacts of different policy pathways on the emission reduction potential of animal husbandry through scenario simulations, providing a scientific basis for decision-makers [163].

Notably, the citations of earth sciences journals (Earth, Geology, and Geophysics) indicate that research may involve cross-cutting issues between land use and soil carbon sequestration. Some studies have further integrated GIS to analyze spatial optimization strategies for pasture management, aiming to reduce land degradation and enhance carbon sequestration capacity.

Overall, the dual-map overlay analysis of the journals indicates that the research paradigm has shifted from a single-core focus on building technology to interdisciplinary collaboration involving energy, information, and materials. It also reflects a broader paradigm shift from isolated research approaches to technology–policy–resource collaborative governance.

5. Discussion

This review highlights the evolution of building stock research from a narrow focus on operational energy efficiency to a holistic paradigm of carbon neutrality. Through a comprehensive analysis of research outputs, thematic shifts, and interdisciplinary integration, this study demonstrates how academic discourse has co-evolved with policy priorities and technological advances. The core contribution of this review lies in its multi-dimensional synthesis, which not only maps the intellectual trajectory of the field but also provides a forward-looking research and policy agenda. In doing so, it offers a unique lens for understanding the systemic transformation needed to decarbonize the global built environment.

5.1. The Paradigm Evolution of BSECER

The paradigm shift in the building sector, from prioritizing energy efficiency to embracing carbon neutrality, represents a significant cognitive evolution in climate change strategies. This transition reflects a move from local optimization efforts to more comprehensive, systematic governance. The previous paradigm, which focused on energy efficiency, was aimed primarily at reducing unit energy consumption. It established a technological framework dominated by improvements in equipment efficiency and the optimization of enclosure structures. During this phase, technological research and policy design focused predominantly on minimizing energy consumption during the operational phase of buildings. Significant achievements were made in energy efficiency research, such as the emission reduction in Chinese residential building operations between 2001 and 2018, which amounted to 2.77 (±1.61) Gt CO₂ [43]. However, the traditional energy-efficiency-oriented approach has certain limitations. For residential buildings, while energy intensity has decreased in many high-income and middle-to-high-income areas, the potential for further improvements is constrained without substantial socioeconomic or technological advancements [164]. Furthermore, the energy conservation and emission reductions achieved through energy efficiency improvements may be partially negated by the so-called “rebound effect” [165]. On a global scale, the rebound effect on energy use could reach 70%, with related emissions potentially rebounding by 90% by 2040 [166].

As carbon neutrality goals deepen, the focus of research has shifted. Buildings are not only perceived as static energy-consuming entities but also as dynamic nodes in the urban carbon metabolism network. This shift highlights the growing recognition of embodied carbon reduction potential. The rise of the carbon neutrality paradigm has marked a new phase in the systematic governance of building emissions. This paradigm centers on achieving net-zero carbon emissions and introduces innovations across three key dimensions. First, the system boundary extends from the operational phase to encompass the entire life cycle of buildings, including material production, construction, operation and maintenance, demolition, and recycling. This broader perspective creates a multiscale network, spanning from individual buildings to communities, cities, and even regions or countries, within the spatial dimension. Second, the evaluation criteria have shifted from focusing on energy consumption to carbon-equivalent accounting. For example, the EU level(s) framework emphasizes the global warming potential (GWP) throughout the building lifecycle [167], incorporating a dynamic carbon budget allocation mechanism. Third, the technological roadmap moves beyond reliance on a single energy efficiency strategy. Globally, the growth of building stock is driving substantial material consumption and environmental impacts. Research indicates that emissions from the building materials sector could be mitigated through increased efficiency until 2060 [104]. Key demand-side strategies include material-efficient design, minimizing material waste, substituting high-carbon materials with low-carbon alternatives, and promoting circular economy interventions such as extending product lifespans, enhancing reusability, facilitating refurbishment, and increasing recyclability [168].

5.2. Limitations and Future Outlook

With the acceleration of global carbon neutrality, the building sector, as an important source of carbon emissions, is facing unprecedented opportunities and challenges in its technological innovation path. On the basis of the analysis of keyword clustering strength, emergent indicators, and temporal evolution characteristics, the current research on low-carbon building renewal presents five characteristic trends. In terms of low-carbon technology, the research focus is shifting from traditional energy efficiency improvement to systematic carbon neutrality solutions. In terms of intelligent applications, emerging technologies such as artificial intelligence (AI) are rapidly developing, but the engineering conversion rate still needs to be improved. In terms of policy tools, scenario analysis methods continue to deepen, but there is insufficient research on regional adaptability. There is a significant gap between technological innovation and system integration in the integration of renewable energy. In terms of interdisciplinary integration, behavioral science and health research are becoming new growth points. These trends collectively outline the key challenges and future directions in the field of low-carbon renewal of building stock.

5.2.1. Low-Carbon Technology and Carbon Neutrality

In the field of carbon management throughout the life cycle of buildings, although existing research has established a basic framework, the degree of refinement is still insufficient [169]. The analysis of keyword timing reveals that, in the future, we need to deepen our research in the following aspects:

• Regional adaptability issues of dynamic LCA methods, especially how to incorporate dynamic factors such as climate characteristics and usage patterns into the evaluation system, need to be studied.
• From keyword timing analysis, it can be seen that circular economy-related research has grown by 18.2% annually, driven by EU policy. The current construction industry still faces challenges such as low material recycling rates and insufficient data transparency, which limit the formation of a closed-loop resource system. In the future, it will be necessary to establish a more comprehensive building information tracking system and a full lifecycle assessment framework to promote resource optimization throughout the entire process from design and construction to demolition. Through technological innovation and policy guidance, the stock of buildings is expected to transform from resource consumers to “urban mines”, providing a stable source of secondary materials for the circular economy [170,171].
• The use of integrated carbon neutrality technology in buildings faces economic bottlenecks [172,173], and the engineering application of new photocatalytic materials will become a breakthrough focus.

5.2.2. Intelligence and Digital Technology

“Artificial intelligence” emerged as an emerging keyword in 2023 (intensity 3.61), but the actual engineering application rate of digital twin technology is still limited [174], reflecting a significant disconnect between theoretical research and engineering practice. The following issues urgently need to be solved:

• In terms of real-time monitoring and optimization of building energy consumption driven by AI, it is also necessary to strengthen the transformation and application of technologies such as digital twins in actual engineering [175].
• The development of building energy efficiency prediction models based on machine learning should be strengthened.
• The application of the Internet of Things in building energy consumption management needs to be promoted [176].

5.2.3. Policy and Scenario Analysis

Scenario analysis tools continue to evolve [177], and the following are some key breakthrough points:

• Simulation of building emission reduction paths in multiple scenarios (such as the 1.5 °C target [178])
• Cases of building stock emission reduction in emerging economies (deepening research on carbon emission accounting methodology for the whole life cycle, especially the standardization of building carbon databases in developing countries [179])
• Urban-scale policy tools include carbon taxes [180], green building standards [181], and green loans [182]
• Policy tool innovation: Exploring the mechanism for linking carbon trading markets to building energy efficiency [183]

5.2.4. Integration of Renewable Energy

Although solar energy research continues to be active, systematic integration research with building stock transformation is still lacking [184], especially in coordinated optimization under the new power system architecture, which needs breakthroughs. Key research directions in the future include the following:

• The combination of distributed energy systems and building stock transformation [185] focuses on breaking through the adaptive integration of PV and energy storage systems with existing building structures [186,187].
• BIPV systems operate in coordination with regional microgrids [188] to optimize the energy scheduling of building complexes.
• Blockchain-based optical storage directs soft building microgrid scheduling algorithms [189,190].
• The development of electric vehicle-building energy system collaborative technology [191,192], including the technical integration of electric vehicles as distributed energy storage units in buildings [193].

5.2.5. Expanding Interdisciplinary Research Dimensions

Future research should focus on breaking through discipline barriers, and frontier directions include the following:

• An interdisciplinary innovation platform should be built, low-cost emission reduction technologies should be focused on, and low-cost intelligent emission reduction plans should be developed [194].
• Research on the relationship between the physical environment of buildings and human health should be carried out to improve the comprehensive benefits of energy-saving transformation [195,196].
• Behavioral economics theory has been integrated, and intervention strategies for user energy use behavior have been explored [197].

6. Conclusions

This study presented a systematic review of global research on building stock energy conservation and emission reduction from 1992 to 2025, revealing distinct temporal, spatial, and thematic patterns in the field. Through bibliometric analysis and network mapping, this study identified key trends, collaborative structures, and emerging frontiers that shaped the trajectory of research on energy conservation and emission reduction in building stock.

6.1. Key Findings

• The Kyoto Protocol came into effect in 2005, with 37 industrialized countries and the European Union committing to reducing greenhouse gas emissions. Since then, global research on this topic has steadily increased. This study compiled a global network of countries, institutions, and author collaborations in the research field. At the national level, China, the United States, and the United Kingdom dominated both in terms of research output and citation impact. Among contributing institutions, Chinese organizations played a particularly prominent role. The Chinese Academy of Sciences, Tsinghua University, Peking University, and Chongqing University frequently collaborated with and were cited by numerous other institutions, reflecting the large-scale collaborative model characteristic of Chinese scientific research. Other major contributing institutions included the Lawrence Berkeley National Laboratory and the University of Colorado in the United States.
• The evolution of research on energy consumption and emission reduction in building stock can be divided into three key stages. The early exploration stage (2005–2010) focused on energy efficiency and the establishment of inventory data systems. The technological deepening stage (2010–2021) marked a shift toward dynamic simulation, transformation strategies, and policy integration. The system integration stage (2021–present) emphasizes carbon neutrality, artificial intelligence, the circular economy, and interdisciplinary approaches. Over time, the research paradigm transitioned from prioritizing energy efficiency to supporting carbon neutrality, reflecting an enhanced understanding of the role of the building sector in climate change mitigation and a shift from localized optimization efforts to a holistic, forward-looking model of sustainable development. Additionally, this paradigm shift involved several key transformations: the system boundary expanded from the operational phase to the entire building lifecycle; evaluation criteria moved from energy consumption metrics to carbon-equivalent accounting; and the technological path evolved beyond sole reliance on energy efficiency, forming a multi-technology, collaborative emission reduction approach.
• Research in this field was centered around four core themes. First, with respect to behavior and operational efficiency, residential behavior significantly influenced energy consumption, whereas the effectiveness of smart technologies and energy retrofits varied considerably across regions. Second, growing attention was given to life cycle and embodied carbon studies, with a focus on material efficiency, recycling, and life cycle assessment. Third, the integration of urban systems with renewable energy became critical for decarbonization. Technologies such as photovoltaic panels, heat pumps, and microgrids were widely adopted; however, their large-scale implementation continued to face challenges in balancing technological feasibility with economic viability. Finally, at the policy and market mechanism level, carbon pricing policies, such as the European Union Emissions Trading System, effectively drove rapid technological responses. Moreover, the evolving standards of green buildings (such as Leadership in Energy and Environmental Design and the Building Research Establishment Environmental Assessment Method) progressively aligned with carbon neutrality goals, highlighting the dual driving role of policy instruments in both research and practical implementation.
• The interdisciplinary knowledge flow between citing and cited journals indicated that research on energy consumption and emission reduction in building stock has become increasingly integrated with environmental science, policy, economics, and digital technologies such as artificial intelligence, geographic information systems, and digital twins. Future research is expected to focus on the advancement of carbon neutrality technologies, such as dynamic lifecycle assessment methods and regenerative materials. Digitalization played a key role, particularly through artificial-intelligence-driven energy optimization and the application of the Internet of Things. Policy innovation was also critical and involved multi-scenario emission reduction pathway modeling and the development of policy tools at the urban scale, such as city-level emission reduction strategies. Renewable energy systems research is increasingly focused on system integration in the context of retrofitting existing building stock. Furthermore, expanding interdisciplinary dimensions, including the integration of behavioral economics theories and studies on the relationship between the physical environment and human health, was essential.

6.2. Research and Policy Implications

Through the analysis of the evolution and core findings in research on energy consumption and emission reduction in building stock, it became evident that a singular focus on operational energy efficiency may have significantly constrained the decarbonization potential of the building sector. While improving energy efficiency and building envelope performance remained important, these measures alone were insufficient to achieve deep emission reductions. Embodied carbon, generated during the production, transportation, construction, and demolition of building materials, accounted for an increasing share of total emissions, particularly in high-efficiency or near-zero energy buildings. Without systematic control of embodied carbon, meeting overall carbon reduction goals will be difficult. To address this, future research and practice need to adopt a more holistic lifecycle assessment approach that captures the full carbon footprint of buildings, from raw material extraction to end-of-life disposal, to ensure scientifically grounded and effective mitigation strategies. In addition to technological optimization, such as integrating renewable energy systems, attention should also be given to the principle of adequacy. This involves achieving low-carbon transformation by reducing resource consumption through measures such as increasing renovation rates to extend building lifespans and managing demand to avoid unnecessary reconstruction.

Moreover, the low-carbon transition of the building sector will depend not only on technological innovation but also on robust collaboration between policy frameworks and academic research. Many innovative methodologies, including dynamic carbon accounting and adequacy-based design frameworks, have not yet been effectively incorporated into policy systems. As a result, their potential to deliver real-world emission reductions remains untapped. Therefore, policymakers will need to establish closer feedback loops with academia and industry, enabling the timely integration of research findings into regulations, standards, and incentive mechanisms. Simultaneously, policy should actively guide research priorities by addressing critical bottlenecks in industry transformation, supporting forward-looking strategies such as embodied carbon quotas and pilot initiatives like regional carbon-neutral building zones. Future efforts are expected to prioritize interdisciplinary integration and foster collaborative innovation among academia, industry, research institutions, and government to enable a comprehensive, systematic, and low-carbon transformation of the building sector.